Understating the Mitigation Challenge, IEA 2008

November 13th, 2008

Posted by: Roger Pielke, Jr.

Last spring along with Tom Wigley and Chris Green we published an article in Nature (PDF) arguing that the IPCC had underestimated the magnitude of the mitigation challenge. Today I’d like to illustrate how the IEA’s World Energy Outlook, published yesterday, also dramatically underestimates the magnitude of the mitigation challenge.

The figure below is taken from the IEA’s publicly-available packet of key graphs (here in PDF). I have annotated it as follows to illustrate how the IEA has significantly underestimated the mitigation challenge.

A. The IEA’s first understatement involves incorrect data about the size of actual global emissions. According to the Global Carbon Project they were about 31.5 GtCO2 in 2007.

B. This curve illustrates what happens if you simply move up the IEA curve to the actual 2007 value, preserving the IEA’s average rate of growth in CO2 emissions of 1.4% per year. The choice of 1.4% per year is puzzling because, as the Global Carbon Project notes, CO2 emissions have been increasing by more than 3.0% per year in recent years. Even with a global economic slowdown, there would seem to be a real possibility that actual emissions growth will occur at a rate faster than 1.4% per year.

C. This curve shows what would happen if CO2 emissions increase at the same rate as energy demand in the IEA reference scenario, which is 1.6% per year, to 2030.

D. And this curve shows what would happen in CO2 emissions increase at a rate of 2.0% per year to 2030. Experience of the current decade shows that even faster rates of growth are possible over extended periods, so this is by no means an upper limit.

You should conclude from this exercise that it is possible, even probable, that the IEA has underestimated the mitigation challenge by a very large amount. Consequently, the IEA’s cost estimates depend upon first assuming a very low rate of growth for carbon dioxide emissions, starting from a misleading baseline. This will have the effect of making the challenge look smaller and less costly (and yet, even in the IEA scenarios the challenge is huge and expensive).

I cannot help but think that mitigation policies are poorly served by getting the scope of the challenge wrong at the outset. I suspect we are dooming them to failure.

10 Responses to “Understating the Mitigation Challenge, IEA 2008”

  1. Roger Pielke, Jr. Says:

    Typo alert — The label for D should say 2% per year. Thanks to an alert reader. I’ll fix soon.

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  3. Roger Pielke, Jr. Says:

    Typo now fixed

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  5. Saint Says:

    Roger: This is a bit unconvincing, Roger. For instance, EIA’s IEO estimates energy-related CO2 emissions were about 28.1 gigatons in 2005. If you apply a (high) 3% annual growth rate, the figure for 2007 comes out to about 29.8 gigatons, which is not all that far off from IEA’s estimate. (A 2% growth rate would yield 29.2 gigatons in 2007, which is just about what IEA estimates.) The Global Carbon Project does fine work, but I’m not convinced its estimates should be treated with any more deference than those produced by IEA, EIA, or other groups. These different estimates do, however, highlight what is really one of the big scandals in this whole climate change debate: We really do not have a good handle on global GHG emissions. And as your analysis shows, even a relatively small error now can translate into a large error (+ or -) down the road.

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  7. Roger Pielke, Jr. Says:


    Thanks, I’m not sure what you are unconvinced about. Co@ concentrations in the atmosphere are well measured, and they match up well with the GCP estimates. For the past several years 3.0% is not a high growth rate, it is low as the actual rate has been estimated at 3.3% (see GCP).

    More importantly, do you really think that 1.4% CO2 growth rate to 2030 should be the basis for policy planning?

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  9. Saint Says:

    Roger: The models I’ve seen use annual growth rates anywhere from about 1.2 to 2.3 percent. EIA’s is about 1.7 percent, if I recall. The IGSM model has at roughly 2.3 percent the highest growth rate of the three models highlighted in the CCSP 2.1 report. I agree with you that 1.4 percent is probably bit on the low side. I guess my larger point is that without better emissions data, particularly from developing countries, we’re stuck debating over which estimate from which source is better, and that has very real impacts on policy, as you suggest. The notion of developing countries aiming for a “significant deviation” below their BAU baseline is one that is gaining a bit of traction, but without proper emissions data and, based on that, reasonable projections, I don’t see how this works.

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  11. Roger Pielke, Jr. Says:

    Hi Saint-

    I’m not sure that future emissions can be predicted with much accuracy. hence, mitigation policy has to be robust to a wide range of possibilities.

    The Pielke, Wigley, and Green Nature paper explained why the models incorporate such low growth rates, as compared to what has actually been occurring.

    The IEA (and others) would be far better served by presenting policies across a much wider range of assumptions, rather than picking out a single set. The IEA policy proposals do not work at emissions growth rates much higher than the baseline. What then? Thanks . . .

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  13. Climate Research News » Emission Impossible: Meaningful Atmospheric CO2 Reductions Says:

    [...] See related post on Prometheus: ‘Understating the Mitigation Challenge, IEA 2008′ [...]

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  15. Hans Erren Says:

    Hi Roger,

    First, the graph in magnification still has the wrong 1.6% label.
    Secondly, I think you underestimate the effect of recessions on emission growth. I plotted Dow Jones year to date growth together with CO2 emission growth, using global emission data from CDIAC:
    So I don’t think the current emission trend is sustainable:

    In the end it all depends how smoothly China will move into real free market economy, and when (not if) the recession will hit China.

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  17. Roger Pielke, Jr. Says:

    Thanks Hans, now fixed. I agree that emissions growth rates are highly uncertain.

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  19. tomfid Says:

    I think point A is incorrect. Eyeballing the graph, IEA is putting current energy-related emissions at between 28 and 29 GtCO2. The GCP report you link puts 2007.5 total emissions at 8.47 GtC or 31 GtCO2, not 31.5. The GCP fossil fuel number is 29.6. GCP includes cement; IEA may not, in which case the GCP number should be deflated to 28.5 for energy-related emissions only. Thus IEA and GCP apparently agree, well within the 5% error cited by GCP.